Of relatively recent vintage is a gun ammunition projectile which is fabricated from two or more metal powders. Commonly, the metal powders are die-pressed into a cylindrical geometry. Such pressed compacts are at times referred to as “cores”. In a common embodiment, to form a projectile, a core is placed in a hollow cup-shaped metal jacket having one end thereof closed and its opposite end open for the receipt of the core. After the core has been placed in the jacket, it is commonly seated against the closed end of jacket. Thereafter, the open end of the jacket, and that end of the core adjacent the open end of the jacket, are die-formed into an ogive. The formation of the ogive tends to partially crush that portion of the core which is involved in the formation of the ogive, generating unbonded and “semi-bonded” metal powder adjacent the leading end of the projectile. In those projectiles where the ogive end of the projectile is not fully closed, this unbonded or semi-bonded powder is free to escape from the jacket, or to move about within the ogive end of the jacket, during handling of a round of ammunition, while the round is in a gun, and/or after the round has been fired and the projectile is traveling to a target.
In U.S. Pat. No. 5,789,698, the present inventor disclosed the use of a solid metal disc disposed within the jacket adjacent the exposed end of the core prior to formation of the ogive. As the ogive is formed, this disc is also deformed and urged toward the open end of the jacket where it defines a cap which seals the open end of the jacket to prevent the escape of metal powder from the ogive end of the projectile and/or to preclude migration of loose powder non-uniformly radially of the longitudinal axis (the spin axis) of the projectile.
In each of the caps of the prior art, the cap has been formed externally of the projectile and thereafter introduced into a metal jacket with a core where the jacket-core-cap subassembly is die formed to define an ogive at the open end of the jacket.
It is an object of the present invention to provide a method for the in-situ formation a cap for use in gun ammunition, particularly ammunition for guns of 50 caliber or smaller calibers, such as the military 5.56 mm round, among others.